1. Field of the Invention
The present invention relates, in general, to an organic metal precursor and a method for forming a metal-containing patterned film on a substrate using the same, and in detail, to an organic metal precursor that enables an electroconductive metal pattern of a micro- or nano-scale to be shaped only by the aid of light without using separate photoresists. The present invention is also directed to a method for depositing a patterned film of a metal or a metal oxide on a substrate via a photo-induced chemical reaction of the organic metal precursor.
2. Background Art
Conventionally, patterned films of metal-containing materials have been made through complicated process involving: depositing a film of an organic metal compound on a silicon or glass substrate by chemical vapor deposition or atomic layer deposition; applying a photoresist film on the organometallic film by spin-coating; and patterning and etching the photoresist film by photolithography. Alternatively, a film of a metal may be deposited on a substrate through plasma deposition, sputtering or electroplating and then coating with a photosensitive resinous film, followed by patterning with light and etching of the resinous film to afford a patterned film of the metal. Unfortunately, these prior techniques generally require high temperature and high vacuum conditions and involve the laborious steps of patterning and etching the films of the photosensitive resin.
Other techniques for forming metallic patterned films have been also proposed which do not depend on photochemical reactions. For example, Japanese Laid-Open Publication No. 62-263973 discloses a patterning method wherein electron beam is irradiated to a thin film of an organometallic compound. In U.S. Pat. No. 5,064,685, organometallic compound-containing ink is applied to a substrate, and then the resulting coating film is allowed to undergo thermal-degradation by being exposed to laser beam radiation to provide a patterned film of a metal. According to this method, the substrate should be subjected to a high temperature condition, and only metal can be deposited.
On the other hand, U.S. Pat. No. 5,534,312 describes that a pattern of a metal can be made through coating a substrate with a metal complex prepared by bonding one or more photosensitive organic ligands to one or more metal atoms, and exposing the substrate to electromagnetic radiation, wherein there is no necessity for applying a photosensitive resin to the coating film of the metal complex. The metal complex consists essentially of at least one ligand selected from the group consisting of: acetylacetonates (both substituted and unsubstituted); dialkyldithiocarbamates; carboxylates; pyridines; amines; diamines; arsines; diarsenes; phosphines; diphosphenes; arenes; alkoxy ligands; alkyl ligands; and aryl ligands. Particularly, in the case where the complex comprises more than one ligand, at least one of the ligands is selected from the group consisting of: oxalato; halogens; hydrogen; hydroxy; cyano; carbonyl; nitro; nitrito; nitrate; nitrosyl; ethylenes; acetylenes; thiocyanato; isothyocyanato; aquo; azides; carbonato; amines; and, thiocarbonyl. When exposed to electromagnetic radiation, the metal complex goes through a photochemical reaction resulting in dissociation of the organic ligands from the central metal atoms, to produce a new metal-containing material adherent to the substrate. However, the rate of such transformation is relatively low, and consequently many hours are required to complete the patterning process, which is the critical problem with this technique.